It was 1997, and the Colts were a completely different team than the one we know today.

In the 13 years since Manning was drafted the boys in blue have seen plenty of highs and plenty of lows, but perhaps only one clear constant: This is Manning’s team, and it is with his presence in mind that the team has ever since been built.

Take away number 18, and the whole thing just seems to fall apart. The no-huddle offense. The “stretch” play. The speedy, explosive defense designed to play with a lead. None of it works without a highly skilled maestro to gently pull its strings. And after a decade of absolute brilliance on his part, it’s almost insulting at this point to imagine anyone but Peyton Williams Manning commanding this ship.

Adam Vinatieri, K

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Nobody really knows what the Colts are like without Manning (no one on the roster has been with the team as long as he has) but there is one difference we all know with absolute certainty: they definitely score fewer touchdowns.

Peyton Manning has produced touchdowns at a pace never seen before. His thirteen consecutive seasons with 25 touchdown passes represent the longest streak in NFL history. The 314 of them he threw between 2000-09 are the most of any decade, And to date, only two quarterbacks who’ve ever played the game have thrown more total touchdown passes than he has, and one of them is likely to lose his spot later this year (assuming Manning returns and does so before too long).

Last year, Manning was personally involved in over 45 percent of all points the Colts offense scored. His efforts helped earn Indianapolis the highest red zone efficiency rating in the entire league, but they also helped limit Adam Vinatieri’s job to that of a glorified human reflex. Vinatieri connected on 51 of his 51 extra point attempts last season, the second most in the league; but he kicked only 28 field goals, tied for the tenth-fewest of all teams.

Suffice it to say that if Manning sits, Vinatieri‘s workload suddenly spikes off the charts.

Lucky for Colts fans, however, if there’s one thing Vinatieri has proven in his illustrious 15-year career, it’s that staying calm and performing under pressure is just what he was born to do.

Vinateiri laughs in the face of pressure. When Vinatieri took his SATs, he didn’t even bring an eraser. He once bought a car in his sleep. The last guy to come up as big as Vinatieri as often as Vinatieri was Casey Ryback, and he’s not even a real person.

If Vinatieri does end up being the guy, then, at least Colts fans know he’ll be ready.

Reggie Wayne, WR

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Reggie Wayne has been a cornerstone of the Colts’ dynamic passing attack for a decade now. And in the event Manning can’t play, Wayne's leadership will be as important to this offense as anything else.

Wayne is a bit of an iron man himself, having started every game for Indianapolis since 2002. His performance over that span has been consistently stellar, too, with over 60 touchdown catches and seven straight seasons with over 1,000 receiving yards. And with all the young receivers the team has developed through the years, it’s no wonder Wayne has grown into a fatherly figure of sorts. After all, it usually doesn’t turn out that way.

It’s obvious that Wayne thinks of himself as a leader, and it’s obvious he’s eager to step into the role.

This Sunday, he just might find himself playing it whether he wants to or not.

Gary Brackett, LB

Manning helps the Colts defense indirectly almost as much as he does the offense directly, and without him, the pressure on Indianapolis’s rambunctious little brother of a unit mounts exponentially.

Gary Brackett is at the heart of that unit, an eight-year undrafted veteran linebacker who knows this defense perhaps better than anyone. Whose efforts have earned him the team captaincy, and who was just recently rewarded with a five-year deal worth $33 million.

Even with all the flak the Colts defense has received over the years, the truth is the offense’s remarkable efficiency has been a tremendous advantage for them. Indy has led the league in third-down conversion percentage three of the last six seasons and has finished in the top five each of those years. And the sad truth is that come Sunday, without the typical touchdown cushion to rely on, we might just find out they’re worse than we ever thought.

It’s Brackett’s job to see that this isn’t the case. If he’s somehow able to rally this defense, make it rise to the occasion and stop an offense that destroyed it to the tune of almost 650 total yards in two games last season, he could very well end up securing a win and earning the group some long-awaited respect in the process.

Joseph Addai, RB

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Joseph Addai is by no means a superstar running back, at least not at this point in his career, but the chance to play without one of the biggest superstar quarterbacks of all time at his side for the first time in his NFL career might actually be considered an opportunity for the sixth-year back out of LSU.

For five years, Addai has done nothing but play a very specific role in the Colts’ pass-happy offense: a decoy.

He’s struggled in that role at times, but he’s shown a few hints of greatness, too. And if the team emphasized the run a little more and went a little easy on the field-marching precision passing game they love so much—which they never should do as long as Manning is still lining up for them—who knows what Addai’s career would look like today?

That’s not to say the guy hasn’t had his opportunities. But what opportunities he has had still have come only within that decoy role.

Take Manning out of the picture, and all the sudden that role disappears. The running game becomes crucial in an instant. It’s not there just to open up passing lanes anymore, it’s there to rack up hard-fought yards. It’s there to move the chains. It’s there because the team needs it in order to win.

If Addai can answer that call, he takes pressure off a quarterback who can’t possibly be too familiar with the offense he’s running yet and makes everybody’s job that much easier.

Dallas Clark, TE

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When news broke eight games into last season that Clark was done for the year and some unknown backup named Jacob Tamme was going to have to fill in for him, Colts fans everywhere shuddered in collective horror.

Then something strange happened.

Tamme not only held his own as the starting tight end on one of the most intimidating offenses in the league, he actually thrived. In eight games, the three-year veteran who’d only started once before in his career racked up over 600 receiving yards and scored four touchdowns. By year’s end only five tight ends in the entire league had caught more passes.

What the Tamme experiment proved, however, is not necessarily that Tamme is an exceptional player or that Dallas Clark is overrated, but more simply that in the Indianapolis system, tight ends are just naturally positioned for success.

That natural matchup advantage could become even more important if a newcomer like Kerry Collins is trying to run the show, someone who needs every edge he can get, that is. And while Tamme has definitely proven even the least likely heroes can emerge from this program, only Clark has the experience and skill set necessary to engage it without Manning behind center.

Dwight Freeney, DE

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While Gary Brackett is the defense’s designated leader, everybody knows its best player is defensive end Dwight Freeney, who signed a six-year, $72 million deal with the team back in 2007 that made him the highest paid defensive player in NFL history at the time.

Freeney is a sack machine and every quarterback’s very worst nightmare. His patented spin move has been analyzed so much even he’s probably sick of hearing about it at this point. He’s posted double-digit sack totals in seven of his nine career seasons, and when it comes to defending the pass, Freeney is about as effective as a single defensive player could possible be.

The problem is that in order to win on Sunday, Freeney is really going to have to earn his paycheck, and in order to do that he’ll have to prove he can also defend the run.

Teams already run all over this defense even with Manning playing, can you imagine what would happen without him, in a low-scoring affair where it’s finally possible for them to sustain a lead?

Jeff Saturday, C

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If this offense didn’t have so many other consistent performers already, Jeff Saturday would probably be recognized for his performance more often than he already is. He has four All-Pro and five Pro Bowl selections to date.

This will be the center’s thirteenth season, all with Indianapolis. He’s played in all but four games since the year 2000, and with him hiking the ball this past decade, Manning has consistently finished as or among the least sacked quarterbacks in the entire league year after year.

As Sunday quickly approaches, however, one can’t help but wonder where Indy would rank in that same category had Kerry Collins, or any other of Manning’s potential backups, been taking all those same snaps?

The truth is Manning has compensated for a weak offensive line for years now. And if it weren’t for his veteran pocket presence and quick release ability, the offensive line would probably have received the same level of scrutiny these past several years that the Colts defense has so memorably suffered.

Collins will not be erasing any of the offensive line’s mistakes this weekend the way Manning often does. And if too many of those mistakes take place, this game could get very ugly very quickly.

Saturday has to step up and bring the rest of the line right on up with him.

Kerry Collins, QB

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As much as Colts fans might hate to admit it, there’s a distinct possibility the team does rise to the occasion on Sunday, sees several star players step up big and somehow still leaves Texas with a big fat “L” branded on their collective foreheads.

When you rely on a single player as much as this team relies on this player, after all, there’s really only so much you can do to compensate for their absence.

Kerry Collins might even prove to be a sufficient substitute and it still might not be enough to win. He could put together a decent game, score a few touchdowns, limit his mistakes and still, when all’s said and done, he could walk away a loser.

Why?

Because this team was built with the assumption that Peyton Manning would be on it and playing, and nothing can change that. There’s no checklist of responsibilities Manning brings to the table that the team can simply delegate to someone else here. There’s no blueprint for replacing him or anything. Not for a player as special as Manning. Not on such short notice. Maybe not ever.

That doesn’t mean Collins can’t win, it just means he could play as good as ever and somehow still lose this game.

Nor does it mean he can’t step up to this challenge, either, and if he does a victory is certainly within grasp.

What it all may very well come down to is the complexity of the Colts offense and the need for a great quarterback to run it.